FISH MANUBB, SULPHATE OF AMMONIUM 65 



phosphate of calcium ; but in- nitrogenous guanos a 

 part exists as phosphate of ammonium, a salt readily 

 soluble in water. 



Guano is sometimes treated with a small proportion 

 of sulphuric acid; it is then called ^'dissolved guano.'* 

 Such guano contains no volatile carbonate of ammo- 

 nium, and nearly the whole of the phosphates has 

 become soluble in water. 



Nitrogenous guano is a highly concentrated manure, 

 and may be employed with excellent effect for corn 

 crops, potatoes, and roots. Phosphatic guanos may 

 be employed for turnips, but such guanos are more 

 usually converted into superphosphate before they are 

 applied to the land. 



Fish Manure.— This consists of fish refuse dried and 

 powdered. It contains usually 7 — 8' 5 per cent, of 

 nitrogen. That made from cod contains 13 — 14 per 

 cent., of phosphoric acid as phosphate of calcium, and 

 that made from haddock and herring 6 — 9 per cent. 

 If much oil is present the value is diminished, as the 

 manure decomposes more slowly in the soil. 



Sulphate of Ammonium,— This substance is prepared 

 from the ammoniacal products of gas works, coke 

 ovens, bone distilleries, &c. In its crystallised form 

 it is the most highly nitrogenous of all the manures at 

 a farmer's disposal, containing 24 — 25 per cent, of 

 ammonia, or 19"8 — 20*6 per cent of nitrogen. 



It should be ascertained that the manure is free 

 from sulphocyanate of ammonium, as this substance is 

 very injurious to plants. If sulphocyanates are present, 

 a solution of the salt will become blood-red on the 

 addition of ferric chloride. 



